Fires
Fires are produced as the result of three components: heat, fuel, and oxygen. Heat produces flammable gases as a result of the pyrolysis (thermal degradation) of polymer, resulting in the breakage of covalent bonds and the formation of a range of intermediate products. An adequate ratio between the flammable gases and oxygen results in the ignition of the polymer. The resulting combustion of the polymer leads to a production of heat that is spread out and fed back. This heat feedback sustains the combustion, resulting in flame spread.
Pyrolysis products that are initially produced as a result of a fire generally consist of a complex mixture of combustible and non-combustible gases, liquids (which may subsequently volatilize), solid carbonaceous chars and highly reactive species, such as free radicals (highly energetic hydrogen and/or hydroxy radicals that propagate the overall combustion process).
Fires occur frequently throughout the world, often causing severe injuries or fatalities to human beings and animals. Each year, over three million fires leading to approximately 29,000 injuries and 4,500 deaths are reported in the United States alone.
In October of 2003, the largest wildfire outbreak in California history caused fires to rage completely out of control for about two weeks in locations within California, including Los Angeles, resulting in a two billion dollar disaster that claimed approximately 3,335 homes and 20 lives. Thousands of California residents were forced to evacuate their homes and relocate to shelters.
Real property (houses, commercial buildings, warehouses, barns and similar structures) and personal property (furniture, electronic devices, appliances, clothing, jewelry, pieces of art, livestock, crops and the like) that are damaged or destroyed by fires can be prohibitively expensive to repair or replace. Certain pieces of personal property, such as photographs, videotapes and pieces of jewelry, are often priceless and irreplaceable. The total annual costs resulting from property losses caused by fires in the United States has been estimated to be over one hundred billion dollars. Personal property losses occur primarily in residences, where furniture, wallcoverings and clothing fuel the fire. Large financial losses may also be incurred when commercial structures, such as office buildings and warehouses, burn. Fires can also produce significant financial losses when they occur in airplanes, trains, ships, buses and other motorized vehicles, where passengers and freight are generally confined, and have a limited means for egress.
Fires frequently cause buildings to collapse, thereby exposing occupants to a risk of severe injury or death from collapsed building materials and falling debris. Although both of the 110-story twin towers of the New York World Trade Center had survived powerful hurricane gusts, and one of them had also survived a bomb explosion in 1993 (creating a 22-foot wide, 5-story deep crater at its base), both of the twin towers collapsed after fires occurred in the buildings following the crash of airplanes into their sides on Sep. 11, 2001. Experts subsequently concluded that structural damage to the towers was caused predominantly by fires, and that this damage was apparently severe enough to overburden the lower sections of the buildings, causing them each to collapse. Thousands of people that had been in the twin towers on Sep. 11, 2001 lost their lives, or were severely injured, as a result of smoke inhalation, falling debris, burning or jumping from windows.
Smoke contains toxic gases, such as carbon monoxide. It is widely acknowledged that carbon monoxide, which incapacitates fire victims, is the most frequent cause of death in building-related fires. The remainder of the deaths in these fires are generally caused by burns and falling building structures.
Fires frequently spread rapidly across products that are present in buildings, such as draperies, rugs, carpeting, upholstery, furniture and other window, wall, floor and ceiling coverings, and produce dense, and often deadly, smoke. Growing concern over the problem of reducing the likelihood of substrates, such as foam in furniture and mattresses, from igniting has prompted the United States Consumer Product Safety Commission to draft proposals that would require these articles not to burn when contacted with an open flame.
Methods for enhancing the flame retardance of consumer goods have been developed to provide protection from fires, and to increase the available escape time from fires.
Flame Retardants
In most cases, organic materials that do not have any flame retardant properties decompose to volatile combustible products when they are exposed to heat and, thus, initiate or propagate fires.
Flame retardant agents can be added to products, such as clothing, to inhibit or suppress the combustion process. The principle effects of flame retardant agents are to inhibit the development of a fire, or to inhibit or delay the spread of fire over a burning material. In actual fires, flame retardant agents generally function to reduce: (a) the heat release rate of a material; (b) the rate of combustion, degradation and consumption of a material (fire extinction); and (c) smoke emission, and the evolution of toxic gases. As a result, flame retardant agents can significantly increase the available escape time before flashover or the development of an incapacitating atmosphere occurs and, thereby, reduce the exposure of human beings and animals to toxic gases and burning.
Flame retardants can act chemically (by reactions in either the gas or solid phase) and/or physically (by cooling, by formation of a protective layer or by dilution of a matrix), and at different times during the combustion process, to inhibit, interfere with and/or otherwise suppress one or more of the following stages of the combustion process in a manner that reduces flame spread over a material and/or the overall heat release: (a) heating; (b) decomposition; (c) ignition; (d) flame spread; and/or (e) smoke production.
Flame retardant compounds can be organic or inorganic compounds containing, for example, halogens, such as chlorine or bromine, phosphorous, alumina and/or antimony. The families of flame retardants include: (a) chlorinated flame retardants; (b) brominated flame retardants; (c) phosphorous based flame retardants; (d) metal hydroxides; (e) melamine based flame retardants; (f) zinc borate; (g) low melting glasses; and (h) silicon-based materials.
Flame Resistance for Fabrics and Textiles
The ability of fabrics, textiles and clothing to retard flame is a highly desirable characteristic to which considerable attention has been directed for public safety. The United States Federal Trade Commission is currently setting standards that require flame retardant fabrics for many end uses of apparel.
Methods are available for developing various types of flame retardant fibers and fabrics. However, these methods generally possess a variety of disadvantages, the principal disadvantage being that the methods are not very durable, particularly to home or industrial launderings or cleaning processes. Fibers and fabrics treated in accordance with these methods generally have an inability to retain flame retardant properties that have been added thereto, or enhanced, after one or more washings, launderings or dry cleaning operations. The added flame retardant properties (and flame retardant agents providing such properties) are generally rendered ineffective, or significantly less effective, as a result of such washings, launderings or dry cleaning operations. Another disadvantage of these methods is that they often result in a waste of large quantities of flame retardant agents, other process components and water, causing these methods to be expensive and potentially detrimental to the environment when they are disposed. The poor recovery rates of process chemicals and solvents employed in flame retarding processes, most of which are lost to municipal waste treatment facilities, as well as required secondary washing process steps, introduce economic, process control and environmental disadvantages to such operations.
Many of the woven and non-woven thermoplastic and non-thermoplastic fibers, fibrous compositions and fabrics that are commonly used today in connection with mattresses, furniture upholstery, insulation and construction materials, and in other commercial, industrial or residential applications, burn when contacted with an open or other flame, sometimes producing toxic gases as a by-product. When treated with a flame retardant composition, thermoplastic fibers, fibrous compositions or fabrics may not burn, but may still melt, producing a molten plastic that can cause deep skin burns. It is this melting of, for example, covering materials, such as the outer surfaces of mattresses, that may allow an open flame to come into contact with other materials, such as non-woven interior construction materials, that the covering materials are supposed to protect, and that may not have been treated with a flame retardant agent.
Another problem associated with non-thermoplastic fibers, fibrous compositions and fabrics is that many non-woven or woven substrate manufacturers do not have the necessary equipment or expertise to add flame retardant agents to these fibers, fibrous compositions and fabrics in their production processes. Increased costs to these manufacturers, thus, may be incurred when roll or other goods or parts need to be shipped elsewhere for flame retarding treatment.
Environmental Impacts of Clothing Manufacture
Several pollution issues currently exist in connection with the manufacture of fabrics, textiles and clothing. As a result, the manufacture of such products often causes one or more of a variety of negative impacts upon the environment. For example, 25% of the insecticides used globally are placed upon cotton plants, which grown cotton to produce the world's most popular fabric. Additionally, many synthetic fabrics, such as polyester, are manufactured from petroleum products that are not biodegradable. Further, many fiber or fabric finishing processes, such as a wide variety of dyeing processes, are highly toxic and polluting to the environment and, thus, are not “environmentally friendly” processes.